The 5.5 replication appliance allows up to 24 historical snapshots. One can retain one replica per day for 24 days or 24 replicas (one per hor) for 24 hours. Recovery always draws the most recent copy but the snapshot manager allows you to revert to an older recovery point.

Changes to Web Client

The vSphere Web Client reflect customer feedbacks, such as the "10 most recent objects). Other
improvements include the new drag and drop support and the ability to filter search results for larger
installations.
Vsphere Flash Card Read

Used to speed up vms; vms page to flash cache (for ssds)

VSAN

Create virtual datastore across spinning disks and ssds
3 hosts minimum
i/o goes first to ssds, then moved to disks
automatic mode and manual mode (similar to drs)
Compatible with vdp, ha, drs, vmotion and vcops
New command: esxcli vsan